1. Field of Invention
The present invention relates to a capacitor and a manufacturing method thereof, and more generally to a capacitor having a metal layer between an electrode and a dielectric layer and a manufacturing method thereof.
2. Description of Related Art
Generally speaking, capacitors are divided into three categories, i.e., metal-insulator-metal (MIM) capacitors, metal-line to metal-line (MOM) capacitors and metal-insulator-silicon (MIS) capacitors. The MIM capacitors are widely adopted among these capacitors.
In the process of forming a MIM capacitor, a bottom electrode is usually formed on a substrate, and a dielectric layer and a top electrode are sequentially formed on the bottom electrode. The step of forming the dielectric layer includes depositing a high-k dielectric material on the bottom electrode. However, the dielectric material may react with the bottom electrode material due to the high process temperature of the deposition, so that the dielectric constant of the formed dielectric layer is decreased, and the capacitance of the capacitor is accordingly reduced. In addition, since the dielectric material reacts with the bottom electrode material, a leakage current is generated during the operation of the formed capacitor.
Besides, after the capacitor is completed, the dielectric material in the capacitor may react with the bottom electrode material in the following backend high-temp processes, so that the performance of the device is affected.